Lime-free removal of non-collagen proteins from sheepskins: Quantitative analysis by gel electrophoresis

Sulfide and lime are the major source of pollution in leather processing. Biotechnological methods have been developed to eliminate the need for sulfide and lime replacing them by enzymes. Removing non-collagen proteins and opening-up the collagen matrix are achieved by the combination of alkali and salts without lime. In this work, samples of sheepskin were digested with three proteases for de-hairing. The non-collagen proteins were removed using NaOH, CaCl₂ and MgCl₂. We have demonstrated that gel electrophoresis techniques can be used for quantitative analysis of the release of nucleic acids and proteins from the enzymatic digested sheepskins. The optimimum condition for de-hairing and removing non-collagen proteins were screened using this technique. We found that the best result for the beamhouse operation or pre-tanning was the combination of enzyme 166 digestion and soaking with a solution of 1.0%NaOH, 0.25-0.75% MgCl₂, 0.25-0.75% CaCl ₂, at 30°C for 16 hours. Sulfide and lime were not required in the process.